Forever by Your Side
by hogwarts-is-frozen
Summary: Written during Frozen Month on tumblr for the age!au prompt. This is a modern!au one-shot where Elsa is much older than Anna and has become her legal guardian - fluffy snow sister antics ensue. *Warning: mentions of death*


**In this AU Elsa is 21/22 and Anna is 6/7. Enjoy!**

The day Elsa got the call that her parents had been killed in a car accident was worst day of her life. She vaguely remembered dropping the phone before her knees gave out and she fell to the floor. Later, she would thank every deity there was that her little sister had not been home at the time. Hadn't been there to see the person who she idolized so much fall apart completely, hadn't been there to see Elsa scream until her lungs burned, and weep until there were no tears left, and turn the house into an arctic wasteland.

Having spent most of her life hiding her mysterious winter magic from her sister until she was old enough, Elsa would never have forgiven herself if she had found out that way. Especially since her powers tended to grow unpredictable and even downright frightening when Elsa was upset. It had taken four hours before Elsa had regained control enough to banish the menacing spines of ice and thick layer of frost that coated the room, her sorrow had been that great.

However, Elsa's grief was briefly overpowered by the dread of having to be the one to turn a six-year old's world upside down. She had to fight the urge to vomit when she heard the bus pull up next to their house announcing the little girl had finished school.

"Hullo! I'm home! Mama, is Elsa still here?"

Elsa forced herself to stop wringing her gloved hands together and swallowed her fear. "I'm still here, Anna."

Elsa's heard a gasp of excitement before a little red-headed girl covered in freckles raced around the corner and into the living room where Elsa stood waiting for her. Anna squealed in delight before running over to her sister and hugging her legs tightly.

"Elsie! I was worried you had gone back to school." Anna was smiling when she looked up at Elsa and it broke the older girl's heart knowing she was going to be the reason that smile disappeared.

Elsa stroked the girl's hair and gave her a tight smile back. "Anna, come sit down with me."

"Okay, I wanna show you what I drew for you in class today. It's a picture of you and me making a snowman. Do you remember? His name was Olaf," Anna beamed as she rifled through her book bag.

Elsa reached over and took the bag from Anna before placing it on the floor.

"Hey!"

"Anna I have something I need to tell you." The room grew a little colder.

The redhead frowned when she noticed how sad Elsa looked. The older girl's eyes were red and puffy, like she had been crying, and when she took Anna's hands in her own the little girl saw that they were shaking.

"What's wrong?"

Elsa swallowed around the lump in her throat. "Anna… honey there was an accident."

Anna didn't move or speak as Elsa tried her best to explain what happened. How did you tell a six-year old that her parents were never coming home, that everything was going to change?

When Elsa put her baby sister to bed that night, the little girl utterly exhausted and cried out, she couldn't help but reach out and brush the bangs away from her face.

She could only hope that things would get better with time.

 _One year later_

"Anna! Anna, where are you?"

Elsa tore through the living room of her modest two-bedroom apartment, eyes darting all around the room in search of twin red braids. Bending over to check under the coffee table Elsa froze when she heard a soft 'click' coming from the other room.

 _Gotcha_.

As quietly as she could the blonde made her way towards the noise, careful to avoid any of the children's toys that littered the floor. She really needed to clean this place up a little… but when? Between work, and classes, and taking care of her sister Elsa had almost no time for things like cleaning, let alone time for herself. And she certainly didn't have time to be hunting down exhausting little sisters.

When Elsa got to her bathroom she paused again and listened. She was about to walk further down the hall when a muffled little sniffle stopped her.

"Anna, I know you're under the sink."

"No you," * _sniff_ * "don't."

Elsa smiled in spite of herself and rolled her eyes. "Unless our bathroom sink has a cold too, I'm pretty sure it's you under there."

"It _could_ have cold. And I told you, I'm not-" a fit of coughing interrupted the little girl's protesting, wiping away Elsa's amused smile and causing her eyebrows to knit together with worry.

Crouching down Elsa slowly opened the cupboard to find a miserable looking little girl with a runny nose and cheeks tinged pink with fever, curled up among shampoo bottles and toilet paper.

Anna looked up at her big sister with tears in her eyes and sniffed again. "Are you mad at me?" Anna asked peering over arms that were securely wrapped around her knees.

Elsa's expression softened. "Of course not, honey, why would you think that?" Elsa said, sitting down on the cold tile of the bathroom floor so that she was level with her sibling.

"'Cause, Mr. Weasel Town," Elsa's lips twitched at the mispronunciation, "said he had to call you at school to come home and take care of me. And you're weird and actually _like_ school, so I know you didn't really want to. I told him I was old enough to stay home by myself but he wouldn't listen." Scowling and looking down at her feet she mumbled, "stupid head," under her breath.

Elsa smiled and shook her head. "No, no you've got it all wrong, silly. You saved me."

Anna looked up at Elsa, her nose wrinkled in confusion, and tilted her head to the side.

"It was my Architecture History class and the professor is so boring that I was actually very happy I had a reason to leave." It wasn't exactly a lie, her professor really was exceptionally dull, but Elsa had been planning on staying on campus to get some studying done. However, she was used to stuff like this happening, she'd learned to just roll with it.

Elsa leaned forward and dropped her voice to a whisper for dramatic effect. "I am pretty sure he was _trying_ to make us fall asleep. I've heard he likes to steal people's socks."

Anna wiped her nose on the back of her sleeve. "Nobody steals socks, Elsa," she said matter-of-factly.

"I dunno," Elsa said with mock seriousness. "He's always got a different pair on whenever I see him."

"You're so weird," the little girl giggled, no longer looking so mopey.

Elsa grinned and stuck her tongue out at her sister, which Anna returned before sneezing rather forcefully, knocking over a few bottles in the process.

The older girl sighed and held out her arms. "Come here."

Anna climbed out of the cupboard, careful not to knock over any more toiletries, and into her older sister's lap.

Elsa stood up and carried the sick little girl to her bed, tucking her in before placing a soft kiss on her forehead. Just as she was about to leave, Anna's sleepy voice stopped her.

"Elsa?"

Elsa turned around to find the girl looking up at her shyly. "Mhmm."

"Can you stay… just for a little while?" Anna asked using those big puppy dog eyes she liked to take advantage of when she wanted chocolate before dinner.

Elsa smiled. "Alright then, scooch over," she said lifting the covers.

Once she was safely under the blanket, Anna shifted so that she was curled into Elsa's side, resting her head on the older girl's shoulder and a hand draped over her stomach. As Anna started to drift off to sleep Elsa hummed an old lullaby their mother used to sing to them whenever they had a bad dream and gently stroked her hair.

They stayed like that for a while, but when Elsa's hand brushed the little girl's cheek she gasped in alarm. "Oh, Anna you're burning up! I am going to go get you some ice." She made to sit up but Anna gripped her tighter to prevent her from doing so.

"Just use _your_ ice," Anna murmured.

"I – what?" Anna could not have just said what Elsa thought she'd said.

"Use _your ice_ ," Anna said more firmly before taking her older sister's hand and peeling off the glove that covered it. Then to Elsa's disbelief, pressed it to her head.

"Anna I don't – I don't know what you're talking about." Elsa stammered, blinking owlishly down at the girl.

"Okay," Anna said yawning loudly and snuggling deeper into Elsa's arms. "Just stay here." Too tired to fight it anymore Anna finally slipped into unconsciousness, mouth hanging open slightly and small fingers still clutching Elsa's shirt.

Elsa was still staring wide-eyed at her little sister but sagged a little in relief. Anna couldn't know, there was just no way… right? The girl must have been imaging things because of the fever. Yes that had to be it. Regardless, Elsa still had to get Anna's temperature down before she got worse. Flexing her ungloved hand, and with a great deal of trepidation, Elsa pressed her palm underneath younger girl's bangs, willing a fine layer of frost to settle there.

When Anna gave a little contented sigh in her sleep Elsa couldn't help but smile as a warmth filled her chest. She soon felt her own eyes growing heavy, but before she could follow her sister into dreamland, Elsa decided that maybe she needed to have a little talk with Anna in the morning.

 **I hope you liked it and sorry for the feels. Please review!**

 ***Also to the guest that reviewed this just now - no, I am not disrespecting canon this is an _alternate universe_. And it seems similar to the relationship between Lilo and Nani _because it is similar._ Just to warn you, if you read my Hunger Games AU Elsa and Kristoff have a similar relationship to Katniss and Gale so watch out for that...eejit.***


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